A number of integrated circuit fabrication processes have been developed that involve depositing thin films on a semiconductor substrate and chemically reacting these films with the substrate at high temperatures and in a controlled atmosphere. Such processes are normally carried out in an apparatus termed a fabrication vessel. A typical fabrication chamber includes a quartz vessel, also termed a quartz tube, coupled to a metallic vessel with a resilient sealing member disposed between the quartz and metal vessels. The sealing member is intended either to form a vacuum seal or, alternatively, to seal the controlled and sometimes high temperature atmosphere within the fabrication chamber and away from the ambient atmosphere. Normally a groove is formed in a flange portion of the metallic vessel for receiving the resilient sealing member. During semiconductor processing, the fabrication chamber may or may not be evacuated to subatmospheric pressures and is typically elevated to high temperatures during which the semiconductor wafer is brought into contact with an atmosphere containing various gases. Unfortunately, the high temperatures maintained in the chamber prior to and during the fabrication process normally causes the temperature of the fabrication chamber itself to substantially increase during semiconductor wafer processing. The resulting high temperature of the fabrication chamber often induces accelerated degradation and premature failure of the resilient sealing member.
A major objective in commercial semiconductor manufacturing is to achieve higher throughput in terms of the number of wafers that are processed over time. One way to significantly increase throughput efficiency is to maximize the number of process runs through a semiconductor fabrication chamber by minimizing chamber down-time associated with the repair and/or replacement of heat damaged sealing members. Thus, some conventional fabrication chambers may include cooling channels or manifold systems integrally included within the body of the metallic vessel portion of the fabrication chamber to lower the operational temperature of the metallic vessel and to increase the useful life of the resilient sealing member.
U.S. Pat. No. 4,556,471, for example, discloses a physical vapor deposition chamber which incorporates a complex manifold system for supplying cooling water to a cathode assembly. Perforations are further provided in the main cooling reservoir surrounding the cathode assembly, however, for also channeling some cooling medium directly into contact with an O-ring seal which provides fluid-tight sealing of the cathode assembly reservoir. This cooling apparatus requires extensive and expensive precision machining of a complex cooling manifold system that is integrally included within the body of the metallic deposition chamber. Moreover, corrosive agents contained within the cooling medium accelerate O-ring seal degradation resulting from direct contact of the O-ring with the cooling medium.
A cooling arrangement for semiconductor fabrication chambers including quartz-type vessels is also disclosed in U.S. Pat. No. 4,641,603 (hereinafter "the '603 chamber"). The fabrication chamber disclosed in this patent includes a dedicated cooling member disposed between a metal base plate and a mounting surface of a quartz vessel. The '603 chamber is apparently intended for sub-atmosphere chemical processing of semiconductor components. To provide a sufficient vacuum seal between the base plate and the quartz vessel, the dedicated channel member of the '603 chamber also includes an O-ring groove for sealing with the quartz vessel. One significant disadvantage of the '603 chamber is, however, the use of at least two O-ring seal members, rather than a single sealing member, to guarantee sufficient vacuum sealing of the fabrication chamber. A first O-ring seal is used to form a vacuum seal between the quartz vessel and the top surface of a cooling member. A second O-ring is provided to form a seal between a metal base plate of the '603 chamber and the bottom surface of the cooling member. Premature degradation or failure of either the first or second O-ring seals, however, will compromise the efficacy of the entire vacuum chamber, and thus decrease the overall semiconductor processing throughput through the '603 chamber.
Thus, there is still a need in the semiconductor manufacturing industry for a cooling apparatus that can effectively reduce the operational temperature of resilient sealing members employed in semiconductor fabrication chambers. There is a further need for a cooling apparatus that is suitable for retrofitting to conventional semiconductor fabrication chambers that lack appropriate cooling apparatus. The present invention fulfills this need.